Leave it alone. It matches the cabinets now, as it should.

I love your idea! Especially if you plan to redo the kitchen in the future, go for it. You could do simple nickel gap shiplap (about $6/board) and paint it the wall color, white or black. You don't have the match the wood color that's there now.

or vertical

Thanks itsourcasa! This is a great idea. I think I am going to do this with the horizontal and paint charcoal to match my table.

Update here when you're done! I love DIY projects.